ABSTRACT
The Earth’s structure The Earth is the third innermost planet of the star we call the Sun. Its structure, as indicated by studying seismic wave records of earthquakes, is made up of a central core, a mantle and a crust (Figure 2.1). The core has a diameter of about 4300 miles (7000 kilometres) and is thought to be composed of two parts. The outer core is about 1300 miles (2100 kilometres) thick and appears to consist of a liquid rock ‘magma’. Beneath this lies the solid inner core having a diameter of around 1700 miles (2700 kilometres), and is believed to consist of very dense rocks composed of 80% iron and varying amounts of nickel, silicon and cobalt.
